Dynamo-electrical vibrating unit



Patented Mar. 6, 1928.

UNITED STATES PATENT oFFic E.

DYNAMIC-ELECTRICAL VIBBATING UNIT.

Application filed June 4,

This invention relates to a dynamo-electrical vibrating unit forconverting electrical pulsations into mechanical movement or vice versa,and its principle objects are to pro vide an instrument which shall:

First. Be highly eflicient, due to the accentuation of the motive forceoperating upon the reciprocating elements.

Second. Consist of few parts.

'lhird. Have these parts of simple construction so that the instrumentshall be easily assembled and easily adjusted.

Fourth. Be economical in cost of production.

Fifth. Be so designed that it shall be readily adaptable to theactivation of radio loud speakers and telephone receivers, as well as toelectric relays, switches and meters.

' A desirable form of this instrument con sists of a permanent magnethaving a general S-shape with like poles at the extremities of the 8these poles being connected to each other by light vibrating reeds orother members capable of conducting the magnetic flux. One of thesereeds is arranged to form the common armature of two coils wound indirectioi'is opposed to each other, by which a like polarity isestablished at the extremities of the arn'iature reed, and the oppositepolarity at the center of the reed, these polarities changing as thedirection of the current flowing through the coil changes. At the sametime, a path for the magnetic flux is providod, paralleling the armatureand connecting the extremities of the S-magnet in the same manner as thearmature. Thismagnetic path may be established by means of an 3 therreed similar to the armature reed, or, in the instance of a. telephonereceiver, it may consist of a soft iron diaphragm.

The auxiliary reed, or the diaphragm, as the case may be, compared withair, provides a path of small reluctance tor the magnetic flux, therebymaking it possible to provide a certain increment to the flux passingthrough the first reed when the coils are energized, this being inaddition to the usual magnetizing eiiect of the coil upon the armaturereed. Hence a greater force is brought to act upon the actuating partsthan would otherwise be the case, and as a result, in the instance of atelephone receiver, a greater force acts upon the diaphragm, which ofcourse produces stronger tones.

The features of this invention for which 1925. Serial No. 34,830.

Fig. 1' represents a. vertical center cross section online 1--1, Fig. 2;

Fig. 2,a bottom plan, exposing the intenor of the instrument, the casingbeing shown in section;

Fig. 3, a section similar to Fig. 1 but show ing a modified constructionof the instrument.

Referring to the drawing, 20 represents a permanent magnet havingsubstantially the term of theletterS with the poles N and S. A reed 2.1of soft steel connects the two N poles to each other, and may beattached to. the permanent magnet by screws 24. Placed around the reed21, which; thereby acts as an armature, are the coils 25' and 25 thesebeing supported by the screws 26 passing: through extended flanges 27 ofthe spool 28 on which the coils are wound. The screws 26 are fastened inthe central branch 20 of the permanentmagnet. Terminals 29 and 30 leadfrom the coils and are connected to the binding posts 31 and 32respectively. The permanent magnet may rest upon. the shoulder 34 thelatter formingan integral part of the casing 34:. A secondmagnetic reed41, in the construction shown in Fig. 3, or a diapln-agm42, in theconstruction shown in Fig. l, in magnetic contact with the permanentmagnet. In either instance the reeds may be ,tensioned by means of thescrews 43 passing through the walls of the casing. In order to moreeasily stress the reeds, saw kerfs 45 may becut in the bends of theSmagnet, thereby causing the bodyof the magnet to ofi'er less resistanceto the screws 4:3.

In Fig. 1 the reed 21 is connected to the diaphragm 452 by means of thetie 46 passing through a hole 47 in the center branch ofthe permanentmagnet. The tie 46 should be made of a non-magnetic substance, such asbrass wire, and berigidly fastened to. the

reed 21 as at 48. The diaphragm 42, may be stressed adjustably againstthe reed 21 by means of the nut 49 threaded on the tie 46.

In the constructionshow-n in Fig. 3, the tie 56 may be secured-to thetwo reeds 2land 4:1, and the diaphragm 52 be adjustably stressed againstthe two reeds, by means of there is a greater increase in the the nut 59threaded on the end of the tie 56.

In the case of a telephone receiver, the ear-piece 60 may be provided,this being threaded on the casing 34. as usual. In the instance of aloud speaker, the cap 70, provided with the usual neck 71 for connectingit to an amplifying horn, may be screwed to the casing 34 in a similarmanner.

The operation of the instrument will now be explained in detail withparticular reference to Fig. 3. When an electric current passes throughthe coils 25 and 25 in the proper direction, the magnetic flux throughthe reed 21 is increased, and naturally strengthens the magnetic pullbetween the pole S and the central portion of the reed 21. The loweredresistance to the magnetic flux offered by the reed 21, combined withthe increased resistance to the passage of the flux in the reed 41,which result from the effect of the current in the coils tending tomagnetize the reed 41 oppositely to the reed 21, establish the oppositepolarity at the center of the reed 41 from that at the center of thereed 21, and cause the flux which previously passed through the reed 41to be transferred to the reed 21. Tplus,

ux through the reed 21, than would normally be produced by themagnetizing effect of the coils upon that reed. alone. This magneticcondition results in the movement of the reed 21 toward the pole S, andof the reed 41 away from this pole. As the reed 21 approaches the poleS, the reluctance of this magnetic path is lowered, and as the reed 41moves away from this pole, the reluctance of the path through this reedis increased because of the widening of the magnetic gap. This resultsin a still greater transfer of magnetic flux from the reed 41 to thereed 21, hence the force tending to move the reeds and the diaphragm,tends also to increase in a greater degree than is ordinarily the case,and thus more nearly approaches the ratio of increase of the resistingforces in the reeds and diaphragm caused by the tension and otherstresses within these elements. I

Since movement of the diaphragm can occur only while the motive forceacting thereupon is greater than the sum of the internal resistingforces, and since it is evident that this condition would prevail overa, greater amplitude of movement of the magnetic elements in thisinvention than would be the case without the reed 41, it follows thatgreater efiicieney in the transformation'o'f electrical energy intosound waves is obtained by theuse of this invention. Also, the movementof the diaphragm is more nearly proportional to differences in thecurrent input, which obviously results in a more natural soundreproduction.

When the current in the coils decreases or reverses in direction, itwill decrease the magnetic conductivity of the path through them, andincrease the conductivity of the path through the reed 41. Thus, theflux will transfer from the reed 2.1 to the reed 41, causing the latterto be attracted to the pole S, and making it easier for the reed 21 tomove away from this pole. This action results in a greatly increasedforce towards the reed 21, and produces a maximum amplitude of movementof the diaphragm.

'lhe reed 41 and the diaphragm 42 may be regarded as auxiliary armatureswith relation to the armature reed 21.

For the reasons stated, this unit gives superior results as an inductiontype microphone.

A sound wave striking the diaphragm causes the downward travel of themovable elements, widening the gap between S and the central part of thereed 21, thus weakening the flux through the coils and inducing currentin them in the usual manner. At the same time, the gap between S and thereed 41 is lessened, thereby making that passage easier, so the fluxwhich previously passed through the reed 21 will be trans ferred to reed41, resulting in a greater drop in the flux passing through the coilsthan would ordinarily occur, thus inducing a greater E. M. F. in them.When the movement of the diaphragm is upward, the lessening oi the gapbetween S and the reed 21 would ordinarily cause an increase of themagnetic flux through the coil. At the same time, however, the gapbetween S and the reed 41 will be increased, accordingly increasing thereluctance of this path to the magnetic flux and causing the latter tobe transferred to the reed 21, thus also causing a greater increase offlux through the Coil, and consequently a. higher E. M. F. to be inducedtherethrough in the opposite direction.

The actions just described, in connection with the construction shown inFig. 3, also hold good for the construction shown in Fig. 1, the reed 41being replaced by the diaphragm 42. When an iron diaphragm is used, theconstruction in Fig. 1 permits a reduction in the number of parts, butwhere a dia 'ihragm of mica or other non-magnetic material is used, itwill be necessary to use the construction in Fig. 3.

Briefly stated, the novel features of this invention consists inproviding two alternating paths or circuits for conducting magneticflux. Each circuit comprises a permanent magnet and an armature, themagnet being common to both circuits. The a l'lfllltlil'Qr are arrangedin spaced relation to each other and connected to maintain thisrelation. lietween' the magnet and one point of each armature, is an airgap, in each instance forming part of the magnetic circuit. Nor- IOUmally, the two air gaps are'equal to each other, but as the twoarmatures are compelled to move in unison, when one armature movestowards the magnet a certain distance, the other armature moves awayfrom the magnet an equal distance, and vice versa Thus when one gap isincreased, the other gap is decreased, obviously resulting in a transferof magnetic flux from the path of high reluctance through the wider gap,to the path of lower reluctance through the narrower gap.

One or more coils are arranged to influence the armatures, so that whenan electric current is sent through the coils, the magnetic conductivityof one circuit will be decreased and that of the other path increased,and the flux therefore be largely transferred from the latter path,resulting in a force tending to move the corresponding armature towardsthe magnet and the other armature away from it. When this movementoccurs, the resultant lessening of the gap in this path and'thesimultaneous increase of the gap in the other path, brin s about a stillgreater transfer of magnetic flux from this other path to the one inwhich the gap is lessening, with a resulting increase in the forcetending to produce motion.

1f the armatures are moved mechanically, the simultaneous increasing ofone gap and the decreasing of the other gap, results in a transfer ofmagnetic flux from one armature to the other, causing an unusually largechange in the magnetic flux through the coil or coils, as the case maybe, consequently inducing an increased E. M. F in them.

B providing alternate paths into which the magnetic flux can bediverted,because of the accelerating or retarding effect of the coilmagnetism, or, in other words, by producing a commutation of the linxthrough alternate magnetic paths, rather than by boosting the flux orchoking it, in a single path, with no alternate path excepting through anon magnetic medium such as air, the force tend ing to produce motion isgreatly increased.

While a specific embodiment of this invention is herein shown anddescribed, all the detailed parts may, or may not be in the preferredforms, and further, the preferred forms may be varied from time to timeas the development of the invention and the arts to which it appertains,progress. Therefore, that which forms an essential part of thisinvention will be discernible from the claims in which its spirit isgeneralized.

Having fully described my invention, what I claim is:

1. A dynamo-electric vibrating unit having a magnet, two complete andseparate magnetic paths across the poles of the magnet, and means forshifting a portion of the magnetic flux from one path so that the saidportion shall completely traverse the other path, or vice versa.

2. A dynamo-electric vibratingunit hav-- ing two magnetic paths, anarmature in each path across the poles ofa magnet, and anelectromagnetic coil arranged to effect an increase in the magnetizationof one armature and a simultaneous decrease in the magnetization of theother armature, or vice versa.

A dynamo-electric vibrating unit hav ing two magnetic circuits, a sourceof magnetism common to both circuits, an armature in each circuit, andan induction coil arranged to oppositely affect the flow of magnetism inthe said armatures, relatively to each other, thus causing a portion ofthe magnetic flux to shift from one armature to the other arn'iature, orvice versa.

t. A dynamo-electric vibrating unit having two magnetic paths, a magnetcommon to both paths, and. electromagnet coils wound in directionsopposed to each other, arranged to exert a shifting effect upon one pathto cause the transfer of a part of its magnetic flux to the other path,or vice versa. 7 5. In a dynamo-electric vibrating unit, the

combination with a magnet having an 8 form, of an armature reedconnecting the extremities of the said magnet to each other, coils woundin directions opposed to each other arranged to act upon said armature,and an auxiliary magnetic member substantially paralleling the saidarmature and also connecting the extremitiesof the said magnet to eachother.

(5. In a dynamo-electric vibrating unit, a.

magnet having an 8 form, magnetic reeds spaced apart from andsubstantially pa alleling each other, extending from one extremity tothe other of the said magnet and in magnetic contact therewith, coilswound in directions opposed to each other, and arranged to directlyinfluence one of the said reeds and to exert a secondary effect on theother reed, a diaphragm arranged in operative proximity to the saidreeds, and

a tie extending from the saidreeds to the diaphragm. I

7. In a dynamo-electric vibrating unit, a permanent magnet having acentral branch, side branches extending outwardly from the centralbranch in directions opposed to each other, magnetic reeds substantiallyparalleling each other and joined to the extremities of the said sidebranches, electromagnetic coils Wound in directions opposed to eachother, placed in operative relation to the said reeds, means fortensioning the said reeds, a diaphragm arranged in proximity to thereeds, and a tie connecting the reeds to the diaphragm.

SQA dynamo-electric vibrating unit com prising a magnet, a plurality ofseparate magnetic paths across the poles of the magnet, and means forincreasing the total magnetic resistance of certain of said paths whilesimultaneously decreasing the resistance of certain other of said paths,thus causing a portion of said flux to shift from certain said paths tocertain other said paths, or vice versa.

9. A dynamo-electric vibrating unit having a magnet, a plurality ofseparate, variable magnetic paths across the poles of the magnetincluding a movable magnetic member, and an electronnlgnct arranged tocause a shifting of a portion of the magnetic flux from certain of saidpaths so that the flux shall completely traverse certain other of thesaid paths andthus exert a force on said magnetic member opposite to theforce previously exerted thereon by said flux, or vice versa.

10. A source of magnetism, a plurality of movable armatnres associatedtherewith, each armature being arranged to complete a circuit carrying aseparate fractioi'i oi the total magnetic flux, and means for rausingthe complete removal of a portion of the magnetic flux from certain ofsaid armatures and a simultaneous addition of this same portion of fluxto certain other of said armatures, or vice versa.

11. A permanent magnet, an :n'mature reed extending from one polarity tothe other polarity of the said magnet, a second armature reed extendingsimilarly from polarity to polarity but located on that side of the saidmagnet opposite to the lirst reed, corresponding portions of each reedbeing iixed to one and the same polarity of the said magnet, while otherportions oi the said reeds are rigidly connected to each other, but arespaced apart from the said other polarity, and means directly operativeupon one of the said reeds for moving that reed relatively to the saidother polarity, thereby varying the gaps between the respective reedsand the said other polarity in inverse proportion to each other.

12. A permanent magnet, an arn'lature reed extending from one polarityto the other polarity of the said magnet, a second armature reedextending similarily from polarity to polarity but located on that sideof the said magnet opposite to the first reed, corresponding portions ofeach reed being lixed to one and the same polarity of the said magnet,While other portions of the said reeds are rigidly connected to eachother, but are spaced apart from the said other polarity, and anelectromagnet directly operative upon one of the said reeds for movingthat rced relatively to the said other polarity, thereby varying thegaps between the respective reeds and the said other polarity in inverseproportion to each other.

13. A dynamo-electric 'ibrating unit having a magnet, a plurality ofseparate alternative magnetic paths for conductance of flux across thepoles of the magnet, a movable magnetic member in each path and anelectromagnetic coil arranged so that a variation of current in saidcoil will simultaneously cause an increase in the total reluctance ofcertain of said paths, and a corresponding decrease in the reluctance ofcertain other of said paths, or vice versa.

it. A dynamo-elmztric vibrating unit comprising a magnet, a plurality ofseparate armatures associated with said magnet, said armatures beingarrmigcd so that a variable air-gap exists between a certain pole ofsaid magnet and each of said armaturcs, and means for simultaneouslycausing an increase in certain of said air-gaps and a correspondingdecrease in certain others of said air-gaps, or vice versa.

15. A dymuno-electric vibrating unit having a single magnet with twoarmaturcs, said armatures being so ititer-connected that they must movein unison with each other, the parts being so arranged that whenmovement of said armatures occurs, the permeability of the path throughone of said armatures, will be increased while the permeability of thepath through the other armatures will be decreased, or vice versa.

In testimony whereof, I sign my name hereto.

THOMAS ll. Ill )WELLS.

